西藏“一江两河”流域油菜需水关键期降水的变化特征

摸清西藏"一江两河"油菜关键生育期降水的气候变化特征,为本区域科学、合理化灌溉提供参考。基于西藏"一江两河"流域9个站1981—2014年逐旬降水量资料,采用算术平均、线性趋势等统计方法,对流域油菜需水关键期的降水特征及趋势变化进行了分析。研究表明:流域油菜蕾苔期和开花期的降水变率较大,多数年份自然降水不能满足作物需水,水分亏缺严重。近34年油菜蕾苔期的降水除江孜表现为减少趋势外,其他各站均呈一致的增加趋势,平均每10年增加0.5~8.6 mm;开花期降水各站均表现出增加趋势,增幅为2.9~10.9 mm/10 a;全生育期的降水量各站以3.9~32.4 mm/10 a的速率呈增加趋势。区域降水增加,水分亏缺量减少,有利于油菜的生长发育。

Precipitation Variation Characteristics in Critical Water Requirement Period of Rape in Central Tibet

The paper aims to understand the climatic change characteristics of precipitation during the critical growth period of edible rape in central Tibet, thus to provide a key reference for scientific irrigation. The authors analyzed the characteristics and changing trends of precipitation during the critical period of water requirement of edible rape with statistics methods, such as arithmetic mean and liner trend analysis, based on a homogeneity-adjusted precipitation data of 9 weather stations in central Tibet from 1981 to 2014. The results showed that the precipitation exhibited a significant variability both temporally and spatially during grey moss and flowering period of edible rape in central Tibet, and the precipitation of most years could not fully satisfy the water requirements of edible rape, indicating a lack of water. In particular, during the past 34 years, the precipitation during grey moss period of rape showed a significant increasing trend with a rate from 0.5 to 8.6 mm/10 a in all stations except Gyantse station, which showed a decreasing trend. The apparent increase in precipitation during flowering stage and whole growth period of rape was found to be at a rate of 2.9-10.9 mm/10 a and 3.9-32.4 mm/10 a, respectively. Overall, the increase in precipitation could mitigate water deficiency in central Tibet, and facilitate the growth and development for edible rape.